When exporting expense data, you can choose to Mark the data as EXTRACTED .  

When exporting expense data and using the Mark as Extracted option, any expense reports that meet the export selection criteria will be marked as extracted regardless of additional filtering that may occur due to expressions such as the !IGNORERECORD! expression.  That is, if an expense report was included in the processing but subsequently filtered out due to an export expression, the entire expense report will still be marked as extracted.

When you choose to mark data as extracted, you can optionally enter a Post Date.  This post date can be any date you choose.  Each time you run an extract and choose to set a post date, the records extracted (or re-extracted) will be marked (or re-marked) with the supplied post date.  The various reports in Unanet that report on expense data, have an option to include output based on this post date.  By default, this field will remain blank unless the user supplies a date to be recorded.

If your site is configured with the Require Post Date On Expense Extraction  (unasense.expense_extract.post_date.required), then you will be required to supply a date value in the Post Date field when clicking the "Mark data as EXTRACTED" option.

Also, when running other expense exports, you can export expenses based on post dates as well.  This may be helpful if you need to feed multiple downstream systems.  You could perform one expense extract (supplying a post date) and choosing to include Completed expenses.  On subsequent exports, you would choose Extracted expenses with the Post Date within the supplied date range.

Note that when you check this option, several other selection criteria options have their choices limited, including;
Certain statuses become unavailable.  See help on those particular selection criteria options for additional information.